Shaking display screens can enhance displayed images on the screen. Projecting an image on a stationary screen using a coherent light source such as a laser light source can result in visual artifacts (known as speckle) in the image area. By shaking the screen surface on which an image is projected, speckle artifacts can be reduced or eliminated. To ensure speckle is reduced over all of the image area on the screen, all of the screen area is shaken. It can be desirable to have more than one point or source of screen vibration to achieve vibrating all of the image area of the screen. Screens can have a large surface area composed of a material, such as vinyl, that absorbs sufficient vibration energy imparted to the screen that the screen requires multiple vibration locations.
Using multiple sources to vibrate the screen, however, can introduce problems.